During next year's bicentennial glut of Verdi and Wagner, steps have been taken to ensure that you do not ignore Britten. The most influential composer ever to draw English breath, Benjamin Britten did more for music in three active decades than all of London's musicians in three centuries. Thomas Beecham's barb, "Well, he's not Great Britten, is he?" has long been laughed into oblivion.

A hundred years after his birth on the grey Suffolk coast that he hugged all his life, Britten's face will appear on the national coinage in 2013 and his music will be played the world over, from Peru to the Palestinian territories. His breakthrough opera Peter Grimes will be staged on the very Aldeburgh beach where its story was conceived. Some 75,000 children will be corralled into Let's Make Music events. A heaving website, britten100.org, has started to hyperventilate. The Britten Year is going to be huge. Let's hope it will also yield affection, and reassessment.

For behind the dental smiles of establishment celebration, Britten's name still evokes discomfort and confusion. His personality was never easy and his work remains troubling for more reasons than he intended. That may be our fault for subjecting his work to a blight of British over-praise.

From the first-night triumph of Grimes, premiered on June 7, 1945, and swiftly staged in 12 countries (Leonard Bernstein gave the 1946 US premiere), Britten, at 31, became an icon of postwar revival, almost above criticism. Two young admirers, Donald Mitchell and Hans Keller, got so excited they launched a magazine, Music Survey, to attest the greatness of Britten and the justness of Schoenberg as twin portals to the musical future. Keller likened Britten to Mozart and, in 1963, called him "the greatest composer alive".

In centennial retrospect, let me suggest that what followed Grimes was small change-the sexless Rape of Lucretia, written for Kathleen Ferrier, and the ho-ho-ho village hall comedy Albert Herring (its narrowed focus weirdly anticipating J.K. Rowling's first post-Potter novel).

Billy Budd reprised the winning theme of man's inhumanity to boys. Britten, announcing "there is no Englishman who is suited to the title role", hired a Californian hunk, Theodor Uppman, to play Budd, opposite Peter Pears and the German-trained Frederick Dalberg. All knew but none reported that Pears was Britten's live-in lover. Domestic sadism was brought unmentionably to stage.

Britten's next peak, after a glutinous Gloriana for the Queen's Coronation, took on yet another no-no. The Turn of the Screw, Henry James's tale of a schoolboy and a predatory ghost, hinted at the composer's liking for pre-teen boys, an urge he just about contained. To sound more modern, he inserted Schoenbergian 12-note rows. Parallel tensions, paedophile and serial, yield two of the most nailbiting hours in the whole of opera. Screw leaves audiences speechless in the intermission. Charles Mackerras called it Britten's "ultimate masterpiece". The centennial should confirm its supremacy.

Composing the unspeakable is the acme of Britten. Screw marked the limits of his daring. What followed was vague, often fruitless quest. On a Far East concert tour with Pears he discovered Japanese noh plays and imitated them in static, unconvincing "church parables". The towering War Requiem of 1962 was regressive, harking back to the modes and tropes of Verdi, Elgar and Anglican liturgy. Death in Venice, a made-for-America retelling of Thomas Mann's boy-fancying novella, was tame enough to be premiered at the Met.

The decade and a half to his early death in 1976 is a gradual creative decline. Yet the sheer scale and variety of his output-from school song to symphony, singalong to string quartet-endorses Keller's judgment that Britten was a musical genius of Mozartian fecundity, if not of consistent quality. We misread Britten if we view the work as being of uniform value-and, further, if we view the work itself as his paramount heritage.

We sail now into disputed waters. Britten's public image is that of a crabby loner in a fishing village, isolated by his sexual proclivities to the point of mild paranoia. A revisionist Penguin biography by the Aldeburgh loyalist Paul Kildea, due next year, is intended as a sanitary corrective to Humphrey Carpenter's boys-and-all shocker. Britten was a fastidious man, terrified of scandal and hypersensitive to personal rejection. No man was quicker to take offence.

The trail of friends he dropped runs halfway around the coastline. "I always felt I was walking on eggshells," said the late Sir John Drummond. "All his life, part of Ben felt that it was him against the world," wrote Lord Harewood. At Aldeburgh, it was said, the safest place to stand was with your back to the sea.

That said, for all his cruelties no man ever did more for his fellow composers. The reasons Britten founded the Aldeburgh festival and prompted Mitchell to create Faber Music were as a refuge for himself and as a nursery for talent. He commissioned composers regardless of creative or stylistic sympathy. It was widely reported that he walked out of the 1968 opening of Harrison Birtwistle's abrasive and violent opera Punch and Judy. Birtwistle has no recollection of any such huff. Britten, he once told me, was cordial and supportive in an aloof kind of way.

His generosity was unconditional, and it did not end with his death. The Britten-Pears Foundation exists to funnel millions of pounds in royalties into the creation of new works and new musical ventures. There is scarcely a British composer of merit who has not received at some needy time the benefit of Britten's disinterested altruism. He is the Rothschild of the musical vineyard.

"So many of the great things in the world have come from the outsider," he reflected, "and that lone dog isn't always attractive." Like J.K. Rowling (and Mozart, perhaps), he was doomed to live out the greater part of his life under the burden of early success. Britten's added tragedy is that he always craved an acceptance he could never achieve. To offset that despair, he decided to improve the state of music, and royally succeeded.

Benjamin Britten converted the former "land without music" into a powerhouse of innovation and enterprise whose musicians stand tall in the world, free of his shadow. He deserves to be embraced in his centenary year with universal gratitude and warmth, uncomplicated by any moral quirks and shortcomings. Great as much of his music is, the man has proved himself greater still.